Abnormal exercise hemodynamics have been reported in patients with hypertrophic cardiomyopathy, including a fall in systolic blood pressure and paradoxical vasodilatation of non-exercising vascular regions. In order to assess whether exercise hemodynamics are different between high risk patients with hypertrophic, cardiomyopathy (cardiac arrest, family history of cardiac arrest, syncope) and patients without these features (low risk), we performed treadmill exercise testing and supine bicycle exercise testing with forearm blood flow measurements with intraarterial blood pressure measurements. There was no difference in the hemodynamic - response to exercise or the change in forearm vascular resistance between high risk and low risk patients. Further, there was no correlation between the change in forearm vascular resistance during exercise and the change in systolic blood pressure. Thus, exercise hemodynamics in patients with hypertrophic cardiomyopathy are not fully explained by changes in resistance of non-exercising vascular beds and do not reliably identify high risk hypertrophic cardiomyopathy patients.